1. Field of the Invention
This invention relates generally to portable pneumatic tools and, more particularly, to compression riveters, used to install solid rivets primarily but not limited to the aerospace industry.
2. Description of the Related Art
Portable pneumatic compression riveters are used to install solid rivets to join parts together. They consist of a valve assembly, cylinder assembly with at least one compression chamber and a head assembly consisting of an alligator style set of jaws or a c-yoke style jaw set. An air line with approximately 90 psi compressed air is connected to the valve. The valve is manually actuated by means of a lever allowing compressed air to enter the cylinder assembly. Inside the cylinder, a piston with a seal and a wedge attached to the front is driven forward by the compressed air. The wedge is driven between a set of bearings mounted within the jaws of the rivet head assembly. The wedge forces the pivoting jaw to pivot about a center pin resulting in a squeezing action out on the end of the pivoting jaw as it closes with the fixed jaw. This squeezing action is the means to upset the rivet to join parts together.
To function most effectively, the valve assembly and cylinder assembly must not leak air. The cylinder material must be both capable of handling the air pressure required to operate the tool and hard enough to resist the wear of the piston. The wedge must be properly aligned with the bearings mounted in the rivet head assembly and capable of handling the resultant forces from upsetting the rivet. A needle roller bearing is typically used with the pivot pin from which the pivoting jaw pivots about. Crushing these needle rollers has long been a limiting factor for this type of tool.
Another shortcoming of the portable pneumatic compression riveters produced today is the potential for catastrophic failure of the pivoting jaw which can lead to injury or damage to the work being assembled when the forward portion of the pivoting jaw reaches its fatigue limit and breaks off from the attached portion at or around the pivot pin area.
One of the major reasons for these shortcomings is the need to make the portable pneumatic compression riveter as light as possible for ergonomic reasons. An improved portable pneumatic compression riveter which addresses these problems and shortcomings of earlier work in this field would be an important technological advance.
It is an object of the invention to provide a portable pneumatic compression riveter which addresses some of the problems and shortcomings of the prior art.
Another object of invention is to provide such a portable pneumatic compression riveter which addresses cylinder, piston and seal wear issues while contributing to a lighter and more reliable seal design.
Another object of the invention is to provide such a portable pneumatic compression riveter which allows for a greater misalignment between the wedge and the bearings in the rivet head assembly and further contributes to reducing the weight of the tool.
Another object of the invention is to provide such a portable pneumatic compression riveter which addresses the problem of crushed needle roller bearings at the pivot pin by utilizing a hardened steel sleeve in place of the needle roller bearing. This further contributes to a lighter, more reliable and compact tool.
Another object of the invention is to provide such a portable pneumatic compression riveter which reduces the chance of catastrophic failure of the pivoting jaw thus reducing the chance of injury or damage to the work being assembled.
Another object of the invention is to provide such a portable pneumatic compression riveter which utilizes a composite valve body to further reduce the weight of the tool. How these objects are accomplished will become apparent from the following descriptions and from the drawings.